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Fluoride anion (F−) with extremely high electronegativity has been under intensive investigation in perovskite solar cells due to its remarkable defect suppression and great improvement of device performance. Nevertheless, these researches only focus on the surface, grain boundaries, or interface modification, the direct insertion of F− into the crystal lattice of regular lead halide perovskite films is still unrevealed. Herein, F− was successfully incorporated into the perovskite lattice by overcoming the insolubility of PbF2 via the introduced pyridinium halide as a novel volatile solubilizing ligand. The strong electronegativity of F− can strongly increase the binding energy of all the ions in CsPbI2Br and inhibit their defect formations. A trace amount of F− incorporation not only enhanced the optoelectronic properties but also effectively mitigated the ion migration and phase separation simultaneously. The photovoltaic performance and operational stability of perovskite solar cells were significantly improved with a champion efficiency of 17.78 % (38.01 %) under AM 1.5G (1000 lux indoor light). Moreover, F− can also be directly inserted into the hybrid perovskite lattice and greatly stabilized crystal‐phase, enabling efficient fully MA‐free FAPbI3 devices with 25.10 % efficiency. Our strategy sheds light on F‐containing perovskites and provides a promising way to tackle ion migration and stabilize the crystal phase in halide perovskites. [ABSTRACT FROM AUTHOR]

Solar‐blind ultraviolet (UV) photodetectors based on p‐organic/n‐Ga2O3 hybrid heterojunctions have attracted extensive attention recently. Herein, the multifunctional solar‐blind photodetector based on p‐type poly[N‐9′‐heptadecanyl‐2,7‐carbazole‐alt‐5,5‐(4′,7′‐di‐2‐thienyl‐2′,1′,3′‐benzothiadiazole)] (PCDTBT)/n‐type amorphous Ga2O3 (a‐Ga2O3) is fabricated and investigated, which can work in the phototransistor mode coupling with self‐powered mode. With the introduction of PCDTBT, the dark current of such the a‐Ga2O3‐based photodetector is decreased to 0.48 pA. Meanwhile, the photoresponse parameters of the a‐Ga2O3‐based photodetector in the phototransistor mode to solar‐blind UV light are further increased, that is, responsivity (R), photo‐detectivity (D*), and external quantum efficiency (EQE) enhanced to 187 A W–1, 1.3 × 1016 Jones and 9.1 × 104 % under the weak light intensity of 11 μW cm–2, respectively. Thanks to the formation of the built‐in field in the p‐PCDTBT/n‐Ga2O3 type‐II heterojunction, the PCDTBT/Ga2O3 multifunctional photodetector shows self‐powered behavior. The responsivity of p‐PCDTBT/n‐Ga2O3 multifunctional photodetector is 57.5 mA W–1 at zero bias. Such multifunctional p‐n hybrid heterojunction‐based photodetectors set the stage for realizing high‐performance amorphous Ga2O3 heterojunction‐based photodetectors. [ABSTRACT FROM AUTHOR]

In this study, the leaching kinetics of magnesium of boron mud (BM) is evaluated using NH4HSO4 solution. The effects of leaching temperature, leaching time, ammonium bisulphate solution concentration and liquid–solid ratio on the extraction ratio of magnesium are investigated. Optimum leaching parameters are determined through an orthogonal test based on single factor experiments. Under the optimum leaching temperature (333 K), leaching time (40 min), NH4HSO4 concentration (2.8 mol · L−1), and liquid–solid ratio (9:1 mL · g−1), the extraction ratio of magnesium was 76.73%. In addition, the leaching kinetics data of magnesium from BM are analyzed through graphical and statistical approaches, which reveal that the leaching process conforms to the grain model. The leaching process is diffusion‐controlled with an activation energy of 41.67 kJ · mol−1. [ABSTRACT FROM AUTHOR]

Perovskite solar cells (PSCs) have exhibited tremendous potential in photovoltaic fields owing to their appreciable performance and simple fabrication. Nevertheless, device performances are still required to be further improved before commercial applications. As one‐dimensional materials, carbon nanotubes (CNTs) have been utilized to regulate stability and efficiency of PSCs because of their excellent chemical stability, flexibility, as well as tunable optical and electrical characteristics. In this review, we comprehensively summarize various functions of CNTs in PSCs, such as transparent electrodes, hole/electron‐transport layers, counter electrodes, perovskite additives, and interlayers. Additionally, applications of CNTs toward the advancement of flexible and semitransparent PSCs are provided. Finally, we preview the challenges and research interests of using CNTs in high‐efficiency and stable perovskite devices. [ABSTRACT FROM AUTHOR]

Biochar and magnesium (Mg) fertilizers have gained increasing attention in agriculture for their potential benefits. However, their combined effects on vegetable growth in southern acidic soils have not been fully elucidated. To address this issue, a study was conducted with six treatments all of which included a baseline amount of compound fertilizer (CK), an increased amount of compound fertilizer (F), Mg fertilizer (M), biochar (BC), biochar combined with Mg (BCM) and an increased amount of compound F with Mg (FM), to investigate their synergistic effects on soil physicochemical properties, enzyme activity, microorganisms and cabbage yield. The results of the study showed that compared with CK, the M, BC and BCM treatments all increased soil organic matter (SOM), exchangeable magnesium (Ex‐Mg), acid phosphatase (ACP) and yield, while the F treatment led to a 5% decrease in SOM. The BCM treatment significantly increased SOM, Ex‐Mg, ACP by 14%, 40%, and 25%, respectively. The most abundant phyla in BCM processing were Proteobacteria (21%), Chloroflexi (19%) and Actinomycetes (17%); the most abundant genera were Bacillus (8%). Further, the effect of BCM on crop growth promotion was better than that of FM, and the economic analysis showed that compared with FM, the benefit of BCM increased by 14%. Through structural equation modelling analysis, the synergistic increase in yield was because of the increase in soil TP, Ex‐Mg, NO3−–N and β‐GC caused by BCM, improving soil nutrients and microbial communities, thereby promoting cabbage growth. Therefore, the combined application of biochar and Mg in acidic soil could significantly improve soil fertility and crop productivity, while also reducing the need for costly chemical fertilizers, thereby offering a promising and cost‐effective approach for sustainable agriculture. [ABSTRACT FROM AUTHOR]

Perovskite solar cells (PSCs) are considered as a promising photovoltaic technology due to their high efficiency and low cost. However, their long‐term stability, mechanical durability, and environmental risks are still unable to meet practical needs. To overcome these issues, we designed a multifunctional elastomer with abundant hydrogen bonds and carbonyl groups. The chemical bonding between polymer and perovskite could increase the growth activation energy of perovskite film and promote the preferential growth of high‐quality perovskite film. Owing to the low defect density and gradient energy‐level alignment, the corresponding device exhibited a champion efficiency of 23.10 %. Furthermore, due to the formation of the hydrogen‐bonded polymer network in the perovskite film, the target devices demonstrated excellent air stability and enhanced flexibility for the flexible PSCs. More importantly, the polymer network could coordinate with Pb2+ ions, immobilizing lead atoms to reduce their release into the environment. This strategy paves the way for the industrialization of high‐performance flexible PSCs. [ABSTRACT FROM AUTHOR]

Compared with the single‐junction perovskite solar cells, the perovskite/perovskite tandem solar cells have the advantages of lower cost and higher power conversion efficiency (PCE). Herein, both two‐terminal (2‐T) and four‐terminal (4‐T) perovskite/perovskite tandem solar cells with all‐inorganic perovskite as the top cell absorption layer and narrow bandgap perovskite MASn0.5Pb0.5I3 material as the bottom cell absorption layer are studied. To effectively improve the photon absorption ratio and performance of the 4‐T tandem device, both reflection and parasitic absorption should be reduced. Afterward, by optimizing the doping concentration of the carrier transport layer, a 4‐T all‐perovskite tandem solar cell with a high PCE of 30.45% is obtained. For the 2‐T all‐perovskite tandem device, the all‐inorganic perovskites with different halogen components (CsPbI3−xBrx, 0 ≤ x ≤ 3) are used as the absorption layer of the top cell, respectively. Through the optimization of the current matching of the subcell, the photoelectric field distribution, the parasitic absorption of the device, etc., an optimal PCE of 27.86% is obtained based on 2‐T CsPbI2Br/MASn0.5Pb0.5I3 tandem device. This study provides a guide for achieving high performance perovskite/perovskite tandem solar cells. [ABSTRACT FROM AUTHOR]

Single‐wall carbon nanotube/silicon (SWCNT/Si) heterojunction shows appealing potential for use in photovoltaic devices. However, the relatively low conductivity of SWCNT network and interfacial recombination of carriers have limited their photovoltaic performance. Herein, a multifunctional Lewis acid (p‐toluenesulfonic acid, TsOH) is used to significantly reduce the energy loss in SWCNT/Si solar cells. Owing to the charge transfer doping effect of TsOH, the conductivity and work function of SWCNT films are optimized and tuned. More importantly, a chemical bridge is constructed at the interface of SWCNT/Si heterojunction. Experimental studies indicate that the phenyl group of TsOH can interact with SWCNTs through π–π interaction, meanwhile, the oxygen in the sulfonic functional group of the TsOH molecule can graft on the dangling bonds of the Si surface. The chemical bridge structure effectively suppresses the recombination of photogenerated carriers. The TsOH coating also works as an antireflection layer, leading to a 19% increment of the photocurrent. As a result, a champion power conversion efficiency of 17.7% is achieved for the TsOH‐SWCNT/Si device, and it also exhibits an excellent stability, retaining more than 96% of the initial efficiency in the ambient air after 1 month. [ABSTRACT FROM AUTHOR]

Rationally managing the secondary‐phase excess lead iodide (PbI2) in hybrid perovskite is of significance for pursuing high performance perovskite solar cells (PSCs), while the challenge remains on its conversion to a homogeneous layer that is robust stable against environmental stimuli. We herein demonstrate an effective strategy of surface reconstruction that converts the excess PbI2 into a gradient lead sulfate‐silica bi‐layer, which substantially stabilizes the perovskite film and reduces interfacial charge transfer barrier in the PSCs device. The perovskite films with such bi‐layer could bear harsh conditions such as soaking in water, light illumination at 70 % relative humidity, and the damp‐thermal (85 °C and 30 % humidity) environment. The resulted PSCs deliver a champion efficiency up to 24.09 %, as well as remarkable environmental stability, e.g. retaining 78 % of their initial efficiency after 5500 h of shelf storage, and 82 % after 1000 h of operational stability testing. [ABSTRACT FROM AUTHOR]

Precocious leaf senescence can reduce crop yield and quality by limiting the growth stage. Melatonin has been shown to delay leaf senescence; however, the underlying mechanism remains obscure. Here, we show that melatonin offsets abscisic acid (ABA) to protect photosystem II and delay the senescence of attached old leaves under the light. Melatonin induced H2O2 accumulation accompanied by an upregulation of melon respiratory burst oxidase homolog D (CmRBOHD) under ABA‐induced stress. Both melatonin and H2O2 induced the accumulation of cytoplasmic‐free Ca2+ ([Ca2+]cyt) in response to ABA, while blocking of Ca2+ influx channels attenuated melatonin‐ and H2O2‐induced ABA tolerance. CmRBOHD overexpression induced [Ca2+]cyt accumulation and delayed leaf senescence, whereas deletion of Arabidopsis AtRBOHD, a homologous gene of CmRBOHD, compromised the melatonin‐induced [Ca2+]cyt accumulation and delay of leaf senescence in Arabidopsis under ABA stress. Furthermore, melatonin, H2O2 and Ca2+ attenuated ABA‐induced K+ efflux and subsequent cell death. CmRBOHD overexpression and AtRBOHD deletion alleviated and aggravated the ABA‐induced K+ efflux, respectively. Taken together, our study unveils a new mechanism by which melatonin offsets ABA action to delay leaf senescence via RBOHD‐dependent H2O2 production that triggers [Ca2+]cyt accumulation and subsequently inhibits K+ efflux and delays cell death/leaf senescence in response to ABA. Summary statement: Melatonin has been shown to delay leaf senescence; however, the underlying mechanism remains obscure. This study shows that melatonin counteracts abscisic acid (ABA) to delay leaf senescence via RBOHD‐dependent H2O2 production that triggers cytoplasmic‐free Ca2+ accumulation and subsequently inhibits K+ efflux and delays cell death in response to ABA. [ABSTRACT FROM AUTHOR]

The ionic nature endows halide perovskites with intrinsic interfacial defects in the formed polycrystalline films, thus imposing the challenge of synchronously passivating these defects with low formation energies that directly account for the unsatisfied performance of perovskite solar cells (PSCs). By virtue of the theoretically proven capability of a three to four times enhancement of the formation energy of each defect of Pb‐I antisite (PbI) and iodine vacancy (VI), a new passivation molecule of 1,10‐phenanthrolin‐5‐amine (PAA) is intentionally explored to synchronously passivate the dual defects. The pronounced passivation effect is experimentally verified by the sharp enhancement of the open‐circuit voltage in ternary PSCs from the original 1.118 up to 1.207 V, as well as the construction of PAA‐modified formamidinium lead iodide PSCs with a champion efficiency up to 24.06%, thus providing a universal alternative of addressing interfacial charge carrier dynamics and operational stability of PSCs that are bothered by the multiple interfacial defects. [ABSTRACT FROM AUTHOR]

CsPbI2Br perovskite solar cells have achieved rapid development owing to their exceptional optoelectronic properties and relatively outstanding stability. However, open‐circuit voltage (Voc) loss caused by band mismatch and charge recombination between perovskite and charge transporting layer is one of the crucial obstacles to further improve the device performance. Here, we proposed a bilayer electron transport layer ZnO(bottom)/SnO2(top) to reduce the Voc loss (Eloss) and promote device Voc by ZnO insert layer thickness modulation, which could improve the efficiency of charge carrier extraction/transfer and suppress the charge carrier recombination. In addition, guanidinium iodide top surface treatment is used to further reduce the trap density, stabilize the perovskite film and align the energy levels, which promotes the fill factor, short‐circuit current density (Jsc), and stability of the device. As a result, the champion cell of double‐side optimized CsPbI2Br perovskite solar cells exhibits an extraordinary efficiency of 16.25% with the best Voc as high as 1.27 V and excellent thermal and storage stability. [ABSTRACT FROM AUTHOR]

Generally, growing phase pure CsPbBr3 single crystals is challenging, and CsPb2Br5 or Cs4PbBr6 by‐products are usually formed due to the different solubilities of CsBr and PbBr2 in the single solvent. Herein, the growth of high‐quality phase pure CsPbBr3 perovskite single crystals at room temperature by a humidity controlled solvent evaporation method is reported first. Meanwhile, the room temperature phase transition process from three dimensional (3D) cubic CsPbBr3 to two dimensional (2D) layered tetragonal CsPb2Br5 and the detailed mechanism induced by humidity are revealed. Moreover, compared with the organic–inorganic perovskite, the prepared CsPbBr3 single crystals are much more stable under high humidity, which satisfies the long‐term working conditions of X‐ray detectors. The X‐ray detectors based on CsPbBr3 single crystals show a high sensitivity and a low detection limit of 1.89 μGyair s–1, all of which meet the needs of medical diagnosis. [ABSTRACT FROM AUTHOR]

All‐inorganic perovskites have been intensively investigated as potential optoelectronic materials because of their excellent thermal stability, especially for CsPbI2Br. Herein, the authors studied the effects of mixed passivation utilizing organic phenylethylammonium bromide and inorganic ionic cesium bromide (PEABr + CsBr) on the all‐inorganic perovskite (CsPbI2Br) solar cells for the first time. The treatment with different passivation mechanisms enhances the perovskite film quality, resulting in uniform surface morphology and compact film with low trap density. Besides, the passivation improves the energy level alignment, which benefits the hole extraction at the perovskite/HTL interface and drives the interface electron separation, suppressing the charge recombination and realizing a high open‐circuit voltage (Voc). Finally, the device represents a high power conversion efficiency (PCE) of 16.70%, a Voc of 1.30 V, and an excellent fill factor (FF) of 0.82. The Voc loss and high FF should be among the best values for CsPbI2Br based devices. Furthermore, the treated devices exhibit remarkable long‐term stability with only 8% PCE loss after storing in a glove box for more than 1000 h without encapsulation. [ABSTRACT FROM AUTHOR]

All‐inorganic perovskite/gallium arsenide (GaAs) tandem solar cells are of great interest for potential space applications. Herein, planar all‐inorganic four‐terminal (4‐T) and two‐terminal (2‐T) perovskite/GaAs tandem solar cells are simulated and optimized, respectively. To achieve higher absorption in the 4‐T configuration, the reflection and parasitic absorption have to be reduced through optimizing the thickness of the perovskite and GaAs base, reducing the thickness of SnO2 and the organic hole transport layer (HTL), and introducing an antireflection coating, respectively. To balance the short‐circuit current and open‐circuit voltage of the GaAs bottom cell, the doping concentration on GaAs is optimized to 1018 cm−3 that has resulted in a high power conversion efficiency (PCE) of 30.97%. Based on the results of 4‐T configuration, all‐inorganic perovskites with different halide compositions are used for current matching to achieve a high‐efficiency 2‐T configuration. After studying the effects of defect density and optimizing the doping concentration of the GaAs base, an extremely high PCE of 30.67% is achieved based on 2‐T CsPbIBr2/GaAs tandem solar cells. Furthermore, the current mismatching under the AM0 spectrum is eliminated for potential high altitude/space application, and the device offers a very competitive PCE of 27.23% compared with that of traditional GaAs double‐junction tandem solar cells. [ABSTRACT FROM AUTHOR]

With the power conversion efficiency (PCE) surpassing 25%, the eye‐catching and promising perovskite materials have proved to be potential competitors in photovoltaic field. Till now, massive efforts have been invested into this blooming flower to further raise its efficiency approaching the Shockley‐Queisser limit (SQ limit) and improve its stability for prolonging effective operation life. In details, various methods including component engineering, structure optimization and interfacial treatment have been used for realizing efficient and stable devices. Especially, the charge transport layers usually play critical roles in effective extraction and transportation of charge carriers. Compared with organic charge transport materials, inorganic materials generally demonstrate excellent stability due to their superior film qualities and inert chemical properties. Moreover, low cost, high charge mobility and material stability have been proved for inorganic electron and hole transport materials. This review summarizes the general progress of different inorganic hole transport materials in perovskite solar cells of recent years for better acquaintance of their contribution in efficient and stable devices. The discussions about performance improvement in the future directions are also provided. [ABSTRACT FROM AUTHOR]

Lead halide perovskites have attracted increasing attention in photovoltaic devices, light‐emitting diodes, photodetectors, and other fields due to their excellent properties. Besides optoelectronic devices, growing numbers of studies have focused on the perovskite‐based electrical devices in the past few years, such as transistors and resistive random access memories (RRAMs). Here, this article summarizes the recent progress the researchers have made of RRAM devices. Primarily, the working mechanism and the key parameters of RRAM are introduced. Generally, the working principles, including the conductive filament model (containing the types of the model of the metal cations‐induced filament and the model of the ions migration in bulk), the interface effect, and the electronic effect are the origins of the RRAM behaviors, and hence, various factors that affect the device performance are explored. Then, RRAMs based on organolead halide perovskite and all‐inorganic perovskite are discussed in terms of different structures, different compositions, and different fabrication methods. Finally, a brief conclusion and a broad outlook are given on the progress and challenges in the field of perovskite‐based RRAMs. [ABSTRACT FROM AUTHOR]

Understanding the crystal anisotropy effect of materials on optical and electrical properties is crucial for further comprehension of the device operating mechanism and device performance improvement. In this study, a detailed theoretical analysis is performed to explore the crystal anisotropy effect on the performance of perovskite solar cells by employing state‐of‐the‐art multiscale simulations connecting from the material (first‐principle theory) to the device (drift‐diffusion model). According to the results obtained from first‐principle calculation, the mobility and absorption coefficient of CsPbIBr2 and CsPbI2Br along the [001] orientation are larger than those along the [100] orientation, suggesting that the transport properties and optical properties along the [001] orientation are superior to those along the [100] orientation. According to the results obtained from the drift‐diffusion model, owing to the superior optical and transport characters along the [001] direction, the optimal power conversion efficiencies (PCEs) of CsPbI2Br (18.88%) and CsPbIBr2 (16.42%) solar cells can be obtained. In addition, the two‐terminal CsPbIxBr3‐x/silicon tandem solar cell is also investigated. By utilizing CsPbIBr2/silicon and CsPbI2Br/silicon tandem structures along the [001] orientation, ultrahigh efficiencies are achieved up to 26.32% and 31.39%, respectively. Therefore, the [001] crystal orientation of CsPbIBr2 and CsPbI2Br is more suitable for further applications of optoelectronic devices. [ABSTRACT FROM AUTHOR]

Recent research shows that the interface state in perovskite solar cells is the main factor which affects the stability and performance of the device, and interface engineering including strain engineering is an effective method to solve this issue. In this work, a CsBr buffer layer is inserted between NiOx hole transport layer and perovskite layer to relieve the lattice mismatch induced interface stress and induce more ordered crystal growth. The experimental and theoretical results show that the addition of the CsBr buffer layer optimizes the interface between the perovskite absorber layer and the NiOx hole transport layer, reduces interface defects and traps, and enhances the hole extraction/transfer. The experimental results show that the power conversion efficiency of optimal device reaches up to 19.7% which is significantly higher than the efficiency of the device without the CsBr buffer layer. Meanwhile, the device stability is also improved. This work provides a deep understanding of the NiOx/perovskite interface and provides a new strategy for interface optimization. [ABSTRACT FROM AUTHOR]

All‐inorganic perovskite CsPbI2Br have been regarded as a promising candidate to tackle the thermal instability issue of organic–inorganic perovskite solar cells. However, the serious interfacial charge recombination and large voltage potential loss in cells circumscribe their performance and commercialization. Herein, a facile approach is demonstrated in which the SnO2 electron transport layer is modified with short‐period deep‐ultraviolet (DUV) photoactivation process to decrease the work function and achieve better energy alignment with the conduction band of perovskites. Such modification triggers efficient charge transfer and reduces the charge recombination. Moreover, first‐principles calculation further demonstrates that DUV‐treated SnO2 can strengthen the interface interaction, reduce the interface stress caused by lattice mismatch, induce more ordered perovskite structure, enlarge transfer charge from 0.71 to 2.33 e, gain larger built‐in field (from 0.74 to 2.09 eV), lower work function, and smaller conduction band offset. Thus, all‐inorganic CsPbI2Br solar cells based on DUV‐treated SnO2 exhibit a significant enhancement in power conversion efficiency, and the champion cell achieves an elevated efficiency of 15.1% with a superior Voc of 1.22 V and better stability. [ABSTRACT FROM AUTHOR]

Perovskite CsPbIBr2 is attracting ever‐increasing attention for carbon‐based, all‐inorganic solar cells, owing to its well‐balanced band gap and stability features. However, significant interfacial recombination of charge carriers in solar cells fabricated with this active layer, which is intrinsically associated with the unwanted conduction band misalignment between CsPbIBr2 and the commonly used TiO2 electron transport layer, has limited power conversion efficiency (PCE) values. Herein, we demonstrate successful conduction band alignment engineering at the TiO2/CsPbIBr2 heterojunction by modifying TiO2 with CsBr clusters. Such modification triggers a beneficial increase in the conduction band minimum (CBM) of TiO2 from −4.00 to −3.81 eV and decreases the work function from 4.11 to 3.86 eV, thus promoting favorable band alignment at the heterojunction, suppressing recombination, and improving extraction and transport of charge carriers. As a result, the carbon‐based, all‐inorganic CsPbIBr2 solar cells exhibit over 20 % enhancement in average PCE. The champion device achieves a PCE of 10.71 %, a record among pure CsPbIBr2‐based cells, open‐circuit voltage of 1.261 V, and excellent stability. [ABSTRACT FROM AUTHOR]

Abstract: NiOx hole transporting layer has been extensively studied in optoelectronic devices. In this paper, the low temperature, solution–combustion‐based method is employed to prepare the NiOx hole transporting layer. The resulting NiOx thin films show better quality and preferable energy alignment with perovskite thin film compared to high temperature sol–gel‐processed NiOx. With this, high‐performance perovskite solar cells are fabricated successfully with power conversion efficiency exceeding 20% using a modified two‐step prepared MA1−yFAyPbI3−xClx perovskite. This efficiency value is among the highest values for NiOx‐based devices. Various characterizations and analyses provide evidence of better film quality, enhanced charge transport and extraction, and suppressed charge recombination. Meanwhile, the device exhibits much better device stability compared to sol–gel‐processed NiOx and poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate)‐based devices. [ABSTRACT FROM AUTHOR]

Organometal halide perovskite as a promising absorber in solar cells has caught tremendous attention in the past few years. Herein, a hydrophobic PCBM layer was introduced into planar heterojunction perovskite solar cells to form the TiO2/PCBM double blocking layer. The bilayer structure assures the formation of a dense, smooth, and pinhole-free blocking layer. And the PCBM layer can also be in favor of larger grain size perovskite film and further passivate the TiO2 blocking layer. Scanning electron microscope, atomic force microscope, and X-ray diffraction (XRD) results suggest the formation of a uniform and compact CH3NH3PbI3−xClx perovskite layer on the PCBM-modified TiO2 blocking layer. The solar cell has reached a PCE up to 16.37%, which is greatly larger than the control device with a PCE of 10.81%. [ABSTRACT FROM AUTHOR]

Efficient inverted organic solar cells (OSCs) with the MoO3 (2 nm)/Ag (12 nm) transparent cathode and an aqueous solution ZnO electron extraction layer processed at low temperature are investigated in this work. The blend of low bandgap poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]] (PTB7) and [6,6]-phenyl-C71-butyric acid methylester (PC71BM) is employed as the photoactive layer here. A power conversion efficiency (PCE) of 5.55% is achieved for such indium tin oxide- (ITO-) free OSCs under AM 1.5G simulated illumination, comparable to that of ITO-based reference OSCs (PCE of 6.11%). It is found that this ZnO interlayer not only slightly enhances the transparency of MoO3/Ag cathode but also obtains a lower root-mean-square (RMS) roughness on the MoO3/Ag surface. Meanwhile, ITO-free OSCs also show a good stability. The PCE of the devices still remains above 85% of the original values after 30 days, which is slightly superior to ITO-based reference OSCs where the 16% degradation in PCE is observed after 30 days. It may be instructive for further research of OSCs based on metal thin film electrodes. [ABSTRACT FROM AUTHOR]

Acene-based materials have promising applications for organic electronics but the major constrain comes from their poor stability. Herein a new strategy to stabilize reactive acenes, by fusion of an anti-aromatic pentalene unit onto the zigzag edges of two acene units to form a Z-shaped acene dimer, is introduced. The Z-shaped acene dimers are extremely stable and show a small energy gap resulting from intramolecular donor-acceptor interactions. X-ray crystallographic analysis revealed their unique geometry and one-dimensional slip-stack columnar structure. Besides optical and electrochemical characterizations, solution-processed field-effect transistors were also fabricated. [ABSTRACT FROM AUTHOR]

High-performance copolyimide (co-PI) fibers were prepared via the wet spinning process of co-polyamide acid precursors based on 3,3′,4,4′-biphenyldianhydride (BPDA) and a mixture of three diamines namely p-phenylene diamine ( p-PDA), 2-(4-aminophenyl)-5-aminobenzimidazole (BIA), and 4,4′-oxidianiline (ODA), followed by drawing and imidization at high temperatures. Effects of the ODA and BIA contents on the molecular packing, morphology, hydrogen-bonding interactions, mechanical and thermal properties of the prepared fibers were investigated. The mechanical properties of the co-PI fibers were improved with the addition of ODA and BIA, and they reached the optimum tensile strength of 2.7 GPa and modulus of 94.3 GPa. Wide-angle X-ray diffraction results (WAXD) showed that the co-PI fibers exhibited highly oriented structure along the fiber direction with low degree of lateral packing orders in the transverse direction. Two-dimensional small-angle X-ray scattering (2D-SAXS) revealed that the incorporation of ODA resulted in the reduction in radius, length, misorientation, and internal surface roughness of the microvoids in the fibers. Fourier transform infrared (FTIR) results indicated that hydrogen-bonding formed between the BIA and cyclic imide units effectively strengthened the intermolecular interactions. The co-PI fibers exhibited excellent thermal and thermal-oxidative stability, with a 5%-weight-loss temperature of 578°C under N2 and 572°C in air. POLYM. ENG. SCI., 55:2615-2625, 2015. © 2015 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

High performance fibers based on copolyimide (co-PI) containing benzimidazole and ether moieties were prepared via a two-step wet spinning method. The effects of draw ratio on the structures and properties of the fibers are investigated. The mechanical properties of the co-PI fibers are improved greatly by increasing draw ratio at temperatures above 400 °C, reaching the optimum tensile strength of 2.8 GPa and modulus of 136 GPa, which is due to the development of the molecular orientation along the fiber direction. The hot drawing process roughens the fiber surface and stretches the molecules in the fibers. Moreover, the fiber structure evolutions during the drawing process were also discussed and a 'smectic A liquid crystal-like' model was proposed. [ABSTRACT FROM AUTHOR]

ABSTRACT The copolyimide (co-PI) fibers with outstanding mechanical properties were prepared by a two-step wet-spinning method, derived from the design of combining 4,4′-oxydianiline (ODA) with the rigid 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA)/ p-phenylenediamine ( p-PDA) backbone. The mechanical properties of PI fibers were drastically improved with the optimum tensile strength of 2.53 GPa at a p-PDA/ODA molar ratio of 5/5, which was approximately 3.7 times the tensile strength of BPDA/ p-PDA PI fibers. Two-dimensional wide-angle X-ray diffraction indicated that the highly oriented structures were formed in the fibers. Two-dimensional small-angle X-ray scattering revealed the existence of the needle-shaped microvoids aligned parallel to the fiber axis, and the introduction of ODA led to the reduction in the size of the microvoids. As a result, the significantly improved mechanical properties of PI fibers were mainly attributed to the gradually formed homogeneous structures. The co-PI fibers also exhibited excellent thermal stabilities of up to 563°C in nitrogen and 536°C in air for a 5% weight loss and glass transition temperatures above 279°C. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42474. [ABSTRACT FROM AUTHOR]

In this work, well-ordered periodic nanogroove structures are constructed on the surfaces of indium tin oxide (ITO) substrates through a simple and cost-effective patterning method, laser interference lithography (LIL). By using the nanopatterned ITO electrodes coated conformally with metal oxide thin films as the electron-selective interlayer (ESL) fabricated by low-temperature atomic layer deposition (ALD), periodically nanostructured cathode-active-layer interfaces are formed in the inverted organic solar cells (OSCs). Compared with a planar-ITO cathode, a nanopatterned ITO cathode with 30 nm high nanogrooves leads to considerably improved short-circuit current and power conversion efficiency for poly(3-hexylthiophene)/[6,6]-phenyl-C61-butyric acid methyl ester (P3HT/PCBM) based cells. The improvement in the photocurrent is caused by enhanced light absorption and improved charge-carrier generation in the devices with nanostructured cathode-active-layer interfaces. [ABSTRACT FROM AUTHOR]

Three soluble and stable thienoacene-fused pentalene derivatives ( 1- 3) with different π-conjugation lengths were synthesized. X-ray crystallographic analysis and density functional theory (DFT) calculations revealed their unique geometric and electronic structures due to the interaction between the aromatic thienoacene units and antiaromatic pentalene moiety. As a result, they all possess a small energy gap and show amphoteric redox behaviour. Time dependent (TD) DFT calculations were used to explain their unique electronic absorption spectra. These new compounds exhibited good thermal stability and ordered packing in solid state and thus their applications in organic field-effect transistors (OFETs) were also investigated. The highest field-effect hole mobility of 0.016, 0.036 and 0.001 cm2 V−1 s−1 was achieved for solution-processed thin films of 1- 3, respectively. [ABSTRACT FROM AUTHOR]

ABSTRACT A pyromellitic diimide building block, 2,6- bis(2-decyltetradecyl)−4,8-di(thiophen-2-yl)pyrrolo[3,4- f]isoindole-1,3,5,7(2H,6H)-tetraone ( 4), is synthesized. Based on this building block and other electron-rich units such as 2,2′-bithiophene, thieno[3,2- b]thiophene and 4,8- bis(dodecyloxy)benzo[1,2- b:4,5- b′]dithiophene, three conjugated polymers P1, P2, and P3 are prepared in good yield via Stille coupling polymerization. These new copolymers have good solubility in common organic solvents and exhibit good thermal stability. The optical, electrochemical, and thermal properties of these polymers P1-P3 are carefully investigated, and their applications in solution-processed organic field-effect transistors are also studied. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 2454-2464 [ABSTRACT FROM AUTHOR]

A series of unsymmetrical naphthalene imide derivatives ( 1- 5) with high electron affinity was synthesized and used in n-channel organic field-effect transistors (OFETs). They have very good solubility in common organic solvents and good thermal stability up to 320 °C. Their photophysical, electrochemical, and thermal properties were investigated in detail. They showed low-lying LUMO energy levels from −3.90 to −4.15 eV owing to a strong electron-withdrawing character. Solution-processed thin-film OFETs based on 1- 4 were measured in both N2 and air. They all showed n-type FET behavior. The liquid-crystalline compounds 1 a, 1 b, and 3 showed good performance owing to the self-healing properties of the film in the liquid-crystal phase. Compound 3 has an electron mobility of up to 0.016 cm2 V−1 s−1 and current on/off ratios of 104-105. [ABSTRACT FROM AUTHOR]

The charge transport layer is crucial to the performance and stability of the perovskite solar cells (PSCs). Compared with other conventional metal oxide electron transport materials, SnO2 has a deeper conduction band and higher electron mobility, and can efficiently serve as an electron transport layer to facilitate charge extraction and transfer. Herein, an optimized low‐temperature solution‐processed SnO2 electron transport layer is achieved by doping polyethylenimine polyelectrolyte into SnO2 for the first time in the PSCs. It is found that the performance of all aspects of the doped SnO2 film is improved over that of the pristine SnO2 film. The better energy level alignment, larger built‐in field, enhanced electron transfer/extraction, and reduced charge recombination all contribute to the improved device performance. Finally, a PSC with a power conversion efficiency of 20.61% is successfully prepared under low temperature below 150 °C. Moreover, the stability of the doped SnO2‐based device is also greatly improved. [ABSTRACT FROM AUTHOR]

Lead‐free halide double perovskites Cs2AgB″X6 (B″═In, Bi; X═Cl, Br, I) are emerging as excellent photoelectric materials. Investigating their mechanical and thermodynamic properties under hydrostatic pressure is vital for designing high‐performance photoelectric devices. Although Cs2AgB″X6 exhibits similar cubic structures, the bond length and strength characteristics of Cs2AgInX6 are different to those of Cs2AgBiX6, and Cs2AgB″X6 exhibits obvious mechanical anisotropic. Upon experiencing pressure, the stablility of Cs2AgB″X6 is improved and without phase transition, and its bond characteristics are unified, which is different to lead halide perovskites. Compared to Cs2AgBiX6, Cs2AgInX6 may be more suitable to flexible devices due to its higher shear and bulk modulus. In addition, the thermal conductivities of Cs2AgBiX6 (X═Cl, Br) and Cs2AgBiX6 (X═Cl, Br, I) are 0.41, 0.32, 0.37, 0.29, 0.23 W m−1 K−1, and can be enlarged by pressure and surpass that of lead halide perovskite. Moreover, all the Cs2AgB″X6 (B″═In, Bi; X═Cl, Br, I) possess the same saturated heat capacity of about 249.3 J mol−1 K−1. These variations of mechanical and thermal properties are elucidated by the bonds. These results maybe also applicable to other double perovskites, and beneficial for designing devices with better optoelectronic performance. [ABSTRACT FROM AUTHOR]

The article looks at research regarding bandgap engineering strategies including impurity and pressure as well as their underlying mechanisms and mentions intermediate band and external electric field for bandgap structure.

Material passivation is essential to enhance the quality of perovskite materials and boost the performance of perovskite solar cells (PSCs). However, most of the previous reports only paid attention to improving the quality of perovskite films by adopting single passivation. Here, a facile strategy that can carry out double passivation to improve the performance of PSCs is demonstrated. By using the dilute halide salt PEABr solution to treat the perovskite film, PbI2 can precipitate from the perovskite. Both PEABr and PbI2 can passivate the perovskite film, and by combining PEABr and PbI2, the double passivation improves the performance of PSCs significantly. Very high short‐circuit current density of 24.30 mA cm−2, open‐circuit voltage of 1.10 V, and fill factor of 79.75% are achieved which lead to a surprising efficiency of 21.32% for the passivated device. The improved efficiency is mainly according to the available surface passivation of the perovskite material, leading to repressed nonradiative recombination and unhindered charge collection. In addition, the passivated device exhibits better power conversion efficiency stability relative to the control device. [ABSTRACT FROM AUTHOR]

In article number 1900293, Jingjing Chang and co-workers demonstrate a novel solution process to develop 2D/3D perovskites with modulated diffusion passivation by introducing a PEAI and DMF additive, which could effectively enhance device performance and long-term stability. The solar cells with passivation treatment exhibit a high fill factor of 83.6% and an average power conversion efficiency of 21.4%. [Extracted from the article]

Perovskite/copper indium gallium selenide (CIGS) tandem solar cells represent an attractive configuration to obtain ultrahigh efficiency. A detailed theoretical analysis is crucial for further improving the performance of tandem solar cells. Herein, four‐terminal and two‐terminal perovskite/CIGS tandem solar cells are intensively researched. For four‐terminal perovskite/CIGS tandem solar cell, the optimal thicknesses of CH3NH3PbI3 and CIGS are 0.5 and 3 μm, respectively, according to the simulation result. Reducing the thickness of TiO2 and Spiro‐OMeTAD can minimize the short‐wavelength parasitic absorption and long‐wavelength parasitic absorption, respectively. Meanwhile, using antireflection coating, such as 100 nm MgF2, is beneficial to increase the photon absorption. For two‐terminal perovskite/CIGS tandem solar cells, the thicknesses of perovskite and CIGS are tuned to meet the current matching. To further improve the efficiency of two‐terminal tandem cells, FTO thickness is reduced to minimize reflection, and the optimal doping concentration of CIGS (1 × 1018 cm−3) is used. In addition, results show that the quality of perovskite films should be improved by enlarging the grain size to decrease the trap states at grain boundary. Finally, the optimal efficiency of two‐terminal CH3NH3PbI2Br/CIGS tandem solar cells reaches 31.13%. [ABSTRACT FROM AUTHOR]

Understanding the interfacial properties of perovskite/SnO2 interface is important for perovskite solar cell design and optimization. Here, interfacial structure and transport properties of CH3NH3PbI3/SnO2 interfaces are investigated comprehensively by density functional theory and experiment. Forming CH3NH3PbI3/SnO2 interfaces weakens the gap states induced by CH3NH3PbI3 surfaces. The interfacial transport properties are strongly dependent on the interface atomic configurations. The CH3NH3PbI3/SnO2 interface with PbI and O terminations is more beneficial for hole blocking and electron transporting due to the largest valence band offset compared to the CH3NH3PbI3/SnO2 interface with other terminations. Moreover, it exhibits a larger electrostatic potential difference compared with CH3NH3PbI3/TiO2 interface, leading to the higher electron transfer efficiency. Hence, higher power conversion efficiency is achieved based on CH3NH3PbI3/SnO2 compared to CH3NH3PbI3/TiO2 structure in experiments. In addition, CH3NH3PbI3/SnO2 interfaces with PbI terminations are more stable than those with CH3NH3I terminations, suggesting PbI2 layer may be preferentially formed on SnO2 substrate during CH3NH3PbI3 fabrication process. Such results could provide a useful understanding on CH3NH3PbI3/SnO2 interface and contribute to new strategies for the interface optimization. [ABSTRACT FROM AUTHOR]

The discovery of two‐dimensional (2D) Ga2O3 has provided an effective way to further tune the performance of β‐Ga2O3. Understanding the effects of strain and electric field (E‐field) on 2D Ga2O3 is helpful to explore the mechanism and potential application in the flexible device. Here, transport and optical properties of monolayer Ga2O3 under uniaxial strain and E‐field are investigated. An indirect‐to‐direct band‐gap‐transition occurs under uniaxial tension due to the different variation of π bonding at the valence bands. The band‐gap exhibits a parabolic variation character from compression to tension, and relates to the direction of uniaxial strain. Interestingly, the transport characters are sensitive to the direction of uniaxial strain, and both compression and tension along b direction enhance the mobility of monolayer Ga2O3, which is inconsistent with that of electron effective mass. The mobility of tensile monolayer Ga2O3 can be enlarged to 48368.14 cm2V−1s−1, different to that of 2D layered materials. Interestingly, the ultra‐visible absorption coefficients are just enhanced significantly by compression along c direction. Upon monolayer Ga2O3 undergoes large E‐field (>0.5 eV Å−1), the band‐gap and anisotropic transport property decreases and even vanishes. The results are useful to reveal the mechanisms and potential of 2D Ga2O3 in the flexible devices. [ABSTRACT FROM AUTHOR]

ZnO is considered as a potential electron transport layer (ETL) in solar cells due to its high charge carrier mobility and low‐temperature processability. However, it is challenging to obtain highly efficient and stable perovskite solar cells (PSCs) using low‐temperature ZnO ETL due to the poor chemical compatibility between ZnO and perovskite films. Hence, proper surface passivation strategies of ZnO ETL are developed to enhance the ZnO/perovskite interface stability for highly efficient PSCs. In this study, low‐temperature TiOx post‐treatment is performed to passivate the ZnO surface, suppress the interface charge recombination, and stabilize the ZnO/perovskite interface. The fullerene treatment is further applied to enhance the electron transfer from perovskite to ZnO and reduce the hysteresis behavior. Finally, high‐performance PSCs with an efficiency of over 20% and improved stability are achieved. [ABSTRACT FROM AUTHOR]

Among all inorganic halide perovskite photovoltaic materials, CsPbIBr2 exhibits the most balanced features in terms of bandgap and stability. However, the poor quality of solution‐processed CsPbIBr2 films impedes further optimization of cells performance. Herein, a facile intermolecular exchange strategy for CsPbIBr2 film is demonstrated, wherein an optimized methanol solution of CsI is spin‐coated on CsPbIBr2 precursor film in conventional one‐step solution route. It surprisingly produces full‐coverage and pure‐phase CsPbIBr2 films featured with average grain size of ≈0.65 µm, few grain boundaries, high crystallinity, preferable (100) orientation, stoichiometric composition along with favorable electronic structures for effective dissociation and transfer of carriers. Hence, the cost‐effective, carbon‐based all‐inorganic planar perovskite solar cells based on them, yield an optimized efficiency of 9.16% with a stabilized value of 8.46% in ambient air conditions that highlight a particularly superb open‐circuit voltage of 1.245 V, all of which represent the highest values reported in pure CsPbIBr2 based cells so far. Moreover, the optimized cell without encapsulation shows excellent long‐term stability because it can retain 90% over 60 days and 97% over 7 days of its initial efficiency, when is stored controllably in ≈45% relative humidity at 25 or 85 °C at zero humidity, respectively. A carbon‐based all‐inorganic planar CsPbIBr2 solar cell with a record efficiency of 9.16%, an extremely high open‐circuit voltage of 1.245 V, and excellent long‐term stability is achieved by a facile intermolecular exchange strategy. Its impressive performance mainly derives from the desirable features of CsPbIBr2 film including full coverage, high crystallinity, preferable (100) orientation, and stoichiometric composition along with favorable electronic structure. [ABSTRACT FROM AUTHOR]